The study includes the testing of amniotic fluid specimens obtained by amniocentesis for therapeutic abortions or with specimens obtained for determination of bilirubin levels. Specimens are being tested for IgM, IgA, and IgG levels. They are also being studied for the presence of virus and mycoplasma organisms. Tissues obtained at therapeutic abortion are also tested for the presence of viruses and myocoplasmas. A new study of placental-fetal tissues for C particles is being started.